Semi‐insulating CdTe single crystals doped with Ga were grown from the vapour phase by the modified Markov technique MMT. The study of the resistivity map in the cross‐sections cut a long the growth direction has been performed. The compensation phenomenon is analysed in the framework of the three levels Fermi‐statistic model. It is shown that a semi‐insulation behaviour throughout the ingot is due to the compensation of shallow impurities by the deep level. From the low ‐temperature photolum inescence spectra it was concluded that shallow donors (GaCd) are partly compensated by (GaCd‐VCd)‐and (GaCd‐CdTe) complexes and by residual acceptors (NaCd, CuCd) . The microscopic structure of (GaCd‐CdTe) complexis proposed based on the value of its local phonon mode and the growth conditions. A native defect like TeCd which has a deep level near the middle‐band‐gap is suppose to give a stable compensation and a tolerance for variation in shallow impurity concentrations.
The temperature dependence of photoluminescence (PL) and photoreflectance (PR) spectra of GaAs1−xNx unrelaxed layers (0⩽x<0.05) grown on GaAs (100) substrates is studied and compared. The energy gap deduced from PR measurements and its temperature dependence are in good agreement with predictions of the band anticrossing model. The main PL peak follows a different temperature dependence, being lower in energy than the energy gap obtained by PR. The observed energy difference between PR and PL is much larger than the typical exciton binding energy, increasing with N content. This result agrees with other works, suggesting that low temperature PL recombination in GaAs1−xNx involves electrons trapped in potential fluctuations due to N concentration inhomogeneities.
The distribution of Er in bulk GaSb ingots grown by vertical Bridgman technique has been investigated for different concentrations. The resistivity, mobility and carrier density were analysed. The formation of Er-Sb compounds and the incorporation of Er at subgrain boundaries has been shown by cathodoluminescence studies.
normalGaSb
(1,0,0) surfaces have been cleaned by chemical passivation and later heat‐treatment in ultrahigh vacuum conditions. Four different etching solutions consisting of an oxidant and an acid for oxide dissolution have been studied. With the
H2SO4:H2O2:H2O
the surfaces become very rough, unevenly covered with oxides, and not suitable for later epitaxial growth. The remaining three etchants studied,
normalHCl:H2O2:normalNaKfalse(normaltartratefalse)
,
HF:HNO3:CH3COOH
, and Br:methanol, leave rather smooth surfaces covered with a thin passivating layer, probably consisting of pure Sb,
Sb2O3
, and
Ga2O3
, which can be easily removed by heating the samples in ultrahigh vacuum at temperatures between 480° and 510°C.
In this work pure and Gd-doped GaSb ingots with different dopant concentrations were grown by the Bridgman Method. The compositional and electrical analysis carried out on these materials have shown the dependence of these results on the initial dopant concentration. The analysis have revealed the presence of inclusions which have been identified as Gd-Sb precipitates. The doped material was found to be p-type with a maximum value of the carrier density at the central region of the ingots. It has been also demonstrated that the Gd enhances the A band emission reducing the band-gap emission.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.